This disclosure relates to a set of electrophotographic toners which are used for electrophotographic machines such as electrostatic copying machines and laser printers.
In electrostatic copying machines (hereinafter referred to as copying machines) which utilize a binary developer comprising an electrophotographic toner (hereinafter referred to as a toner) and a carrier, an initial supply toner is contained together with a carrier in a developing apparatus from the beginning of the copying process, while a supplementary toner is contained in a toner hopper. The toner contained in the developing apparatus is mixed with the carrier in this apparatus, resulting in a developer. The developer formed in this way is supplied either to a photosensitive drum by magnetic rollers or to a donor roll, from which a toner layer is presented to a photosensitive drum. The toner contained in the toner hopper is supplied to the developing apparatus when a decrease in toner concentration in the developer contained in the developing apparatus is observed by a sensor for detecting toner concentration. Thereafter, the toner supplied to the developing apparatus is mixed with a carrier to form a developer which is then supplied to the photosensitive drum in the same way as mentioned above. The toner contained in the developer is adsorbed by an electrostatic latent image which has been formed on the photosensitive drum, and then transferred to paper, resulting in a desired toner image thereon.
The toner remaining on the surface of the photosensitive drum after the transfer to paper is scraped off the surface of the photosensitive drum by a cleaning blade in a cleaning apparatus.
In conventional copying machines, the supplementary toner contained in the toner hopper is the same as that contained in the developing apparatus from the beginning of the copying process. Usually, the toner mentioned above is composed of toner powder and additives adhering to the surface of the toner powder. This toner powder is obtained by mixing the material used, kneading the mixture, grinding the mixture into powder, and sizing the resulting powder to have a desired mean particle size. An alternative manufacturing method involves a chemical process to aggregate and coalesce smaller particles to form toner of the correct final size. As the additives to be used for the toner, there can be mentioned, for example, charge-controlling agents and cleaning agents.
The present disclosure is generally directed to toner and developer compositions, and more specifically, is directed to processes for controlling developer aging characteristics. In embodiments to be described hereinafter, the present disclosure relates to development wires in printing platforms that are sensitive to the state of the developer material. The state of the material can change or age over time. To mitigate the changes to the developer state, bare carrier can be added to the developer housing at a constant rate. This process is known as carrier dispense. Carrier dispense is costly; and therefor it is desirable to reduce the amount of carrier dispensed while maintaining the same level of developer performance.
In addition to the benefits of adding new carrier to developer, it is also known that dispensing small amounts of fresh toner can improve performance after extended runs of low area coverage. The benefit is due to the toner additives on the surface of the fresh toner.
The toner and developer compositions of the present disclosure, in embodiments thereof to be described hereinafter, provides for the current carrier dispense system to be used to transport toner additives directly into the developer housings to maintain developer performance. The additives could be attached to the surface of carrier beads. The toner and developer compositions of the present disclosure can be selected for electrophotographic, especially xerographic imaging and printing processes, including color processes.